Various mobile machines, especially mobile agricultural machines, include earthworking implements arranged on laterally extending tool bars or wing frames. To accommodate transportation of such a machine along a highway, means are provided for pivotally swinging or folding one or more of the wing frames upwardly from a lowered ground-engaging position to a raised, inactive position.
Various conventional or non-conventional actuators may be employed to raise the wing frames. Once the wing frames are raised to the inactive position, mechanical or hydraulic locking systems are engaged to prevent the inadvertent lowering of the wing frames. For example, wing frames are typically raised with hydraulic actuators. In such a situation hydraulic fluid leakage in the valves, seals, lines, fittings or other places could permit the weight of the wing frames, or other imposed forces, to cause the wing frames to be lowered in the absence of locking systems.
Mechanical wing frame locking systems typically require that the operator raise the wing frame by operating the controls on the machine, dismount the machine and walk to the wing frame, insert a locking pin to secure each wing frame to a portion of the main frame, and then mount the machine again.
In addition to the disadvantages inherent in this labor intensive process, it is possible for the operator to forget to carry out the wing frame locking process altogether. Further, even if the wing frames are properly locked in the raised positions, it is possible for the operator to forget to remove the locking pins before operating the actuators to lower the wing frames. This could cause damage to the machinery. To avoid this possibility, the machinery could be structurally designed to accommodate the situation in which the operator forgets to remove the locking pins. However, this would increase the cost of the machinery.
Attempts to overcome the disadvantages of mechanical locking pin systems for maintaining wing frames in the raised, inactive positions have involved the use of automatically operated lock-up systems employing hydraulic actuators. Such lock-up systems are more expensive, requiring the use of additional hydraulic piston-cylinder actuators, valves, and hoses.
It would be desirable to provide an improved wing frame folding apparatus with automatic lock-up capability. It would be advantageous to provide such an apparatus wherein the lock-up capability could be automatically effected without requiring more complex and costly hydraulically operated latch mechanisms.
Further, it would be desirable to provide such an improved wing frame lock-up apparatus with means for ensuring that each raised wing frame can be positively urged back to the ground engaging position.
Finally, it would be beneficial to provide a wing frame assembly with a lock-up system that will permit pivoting movement ("float") of the wing frames when the wing frames are in the lowered, ground engaging positions so as to accommodate vertical variations in ground terrain.